narcotic, any of a number of substances that have a depressant effect on the nervous system. The chief narcotic drugs are opium, its constituents morphine and codeine, and the morphine derivative heroin.

See also drug addiction and drug abuse.

Actions and Uses

In small doses narcotics have valuable medical uses, numbing the senses, relieving severe pain, and inducing sleep. They are also given preoperatively to relieve pain and anxiety. Common side effects include constipation, nausea, and allergic reactions. In large doses narcotics can be highly dangerous, causing stupor, coma, convulsions, or death. All narcotics are addictive; several morphine derivatives as well as chemically dissimilar narcotics that have been developed for medical use have fewer side effects and are less addictive than morphine, but they are also generally less potent. Unlike general anesthetics such as ether and chloroform, narcotics depress the respiratory center and in low doses relieve pain without inducing sleep. Respiratory depression occurs in newborns whose mothers have been given narcotics such as meperidine (Demerol) during labor. Narcotics differ from barbiturates and other sedatives in that they have no anticonvulsant action; also, narcotics relieve pain, while sedatives do not.

Attempts at Control

There are strict controls on narcotic prescription and administration in the United States. Nevertheless, addiction to narcotics, especially heroin, which has no legal use, continues to be a serious problem. There have been nationally and internationally based attempts to control the production of narcotics and to limit their export and import to medical use only. Large quantities are nonetheless grown in the "Golden Triangle" region of Myanmar and Thailand (cultivation in Laos was largely eradicated in 2005) and in SW Asia (e.g., Afghanistan, Iran, and Pakistan), Lebanon, Mexico, and Guatemala, and a large illicit traffic in these substances continues.

Drug that produces analgesia (see analgesic), narcosis (stupor or sleep), and drug addiction. In most people narcotics also produce euphoria. Those that occur naturally in the opium poppy, notably morphine, have been used since ancient Greek times. The main therapeutic use of narcotics is for pain relief. Most countries limit the production, sale, and use of narcotics because of their addictive properties and detrimental effects and the incidence of drug abuse. With the development in the 19th century of the hypodermic needle and of heroin, five to 10 times as potent as morphine, the use and abuse of narcotics increased dramatically. A narcotic overdose can cause central nervous system depression, respiratory failure, and death.

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